Nano-coating material, method for manufacturing same, coating agent, functional material, and method for manufacturing same

ABSTRACT

A nano-coating material, capable of being bonded to the surface of a metal or an alloy substrate, the nano-coating material includes a compound having, in a polymer main chain, (A) a first side chain or a terminal, each having a binding group containing a benzene ring having at least one pair of adjacent hydroxyl groups; and (B) a functional second side chain.

TECHNICAL FIELD

The present invention relates to a nano-coating material, a method forproducing the same, a coating agent, a functional material, and a methodfor producing the functional material.

BACKGROUND ART

Metals such as magnesium (Mg), aluminum (Al), titanium (Ti) and copper(Cu), alloys containing those metals as main components, and steelcontaining iron (Fe) as a main component, are utilized as structuralmaterial components appropriate for engineering applications.

For example, Mg among these is an element that is abundant in theearth's surface, and is known to be a metal that can be used forengineering applications, is light, has high toughness per unit mass,has high vibration absorbability, is non-toxic, and has satisfactorycastability. Therefore, Mg is an important metal that is utilized inindustrial application and daily goods. In fact, Mg is used inautomotive wheels, aircraft parts, mobile telephone components, and thelike.

However, metal elements such as Mg described above are reaction-activesubstances, and readily react with water molecules, halide ionsincluding chloride ions, or the like in air or in water to be oxidized.Through this oxidation reaction, these materials have a problem thatrust containing the reaction active substances as main components isgenerated and deteriorates durability. For example, when Mg is immersedin an acidic solution, an alkaline solution, or saline, Mg immediatelyundergoes a chemical reaction represented by the following chemicalformula (1), and is corroded along with the generation of hydrogen.

$\begin{matrix}{\left\lbrack {{Chemical}\mspace{14mu} {Formula}\mspace{14mu} 1} \right\rbrack \mspace{506mu}} & \; \\\left. \begin{matrix}\left. {Mg}\rightarrow{{Mg}^{n +} + {ne}^{-}} \right. \\\left. {{2n\; H^{+}} + {2\; {ne}^{-}}}\rightarrow{n\; \left. H_{2}\uparrow \right.} \right.\end{matrix} \right\} & (1)\end{matrix}$

Such an oxidative deterioration reaction becomes particularlyproblematic when a non-noble metal such as Mg is used as a structuralmaterial. In the case of an Al alloy or steel, since the oxide filmproduced on the alloy surface works as a passivation film, oxidation ofthe alloy matrix itself can be prevented. On the other hand, since a Mgalloy or the like has high corrosion activity, it is difficult toproduce a stable passivation film.

Therefore, in order to suppress corrosion reactions, anti-rust coatingmaterials that protect the surface of metal substrates such as Mg and Mgalloys, and the like have been hitherto developed to enhance anti-rustproperties.

For example, there has been suggested a method for producing a corrosionresistant iron material having high antirust properties and durabilitythereof, without using or including any chromium-based compounds thathave antirust properties but are hazardous (Patent Literature 1). Inthis case, the corrosion resistant iron material is coated with anantirust coating composition that includes a compound having at leastone phenolic hydroxyl group in the molecule and a silane compound asessential components. However, in Patent Literature 1 of the prior art,the composition was not applied to magnesium alloys, which have highcorrosion tendency and are not very effective to anti-corrosiontechnologies.

In the case of copper alloys, it has been traditionally known thatnitrogen-containing aromatic compounds such as benzotriazole exhibitsuperior performance as corrosion inhibitors (Non-Patent Literature 1).It is considered that when such a corrosion inhibitor is used,non-covalent bonds are formed between the atoms at the metal surface andthe ligand present in corrosion inhibitor, and finally thenitrogen-containing aromatic compound molecules form a two-dimensionalpolymer network in atomic level, so that an antirust effect can beobtained thereby. That is, it is disclosed that, as a result of themetal-ligand interaction in atomic level and the corrosion inhibitorcompactly and completely covering the surface of the metal substrate,hydrogen, chlorine, water and the like are effectively removed, andconsequently, the nitrogen-containing aromatic compounds exhibit highanti-corrosion properties for copper and copper alloys.

However, the antirust effect of such a nitrogen-containing aromaticcompound is a phenomenon limited to copper and copper alloys, and anorganic coating agent which exhibits an antirust effect irrespective ofthe kind of metal has not yet been developed.

Furthermore, a surface-treated metal plate that does not contain anyhexavalent chromium, which imposes high environmental toxicity, andexhibits excellent corrosion resistance, solvent resistance, alkaliresistance and adhesiveness to top coat materials, and a method forproducing the surface-treated metal plate have been suggested (PatentLiterature 2). In the surface-treated metal plate of this case, asurface treating agent containing an organic resin having an anionicfunctional group is applied on the surface of the metal plate or thelike, and after heating and drying, a surface treatment coating film isformed through contact with an aqueous solution containing a metalcation such as Mg²⁺.

However, the antirust effect of these conventional antirust coatingmaterials and the like was not sufficient in any of the cases.Furthermore, in the case of using these antirust coating materials, acoating agent must be developed and produced for each kind of metal oralloy or each composition, and the operation was complicated. Moreover,in a case in which such an antirust coating material was used, if athick film having a thickness of about several dozen μm was not formed,it was difficult to secure the adhesive power for a metal, or to preventpenetration of water or halide ions through cracks of the coating film.Therefore, in a case in which antirust coating is applied to a finelyprocessed product that uses an alloy, using these antirust coatingmaterials, there occurs a problem that the delicate processing isimpaired. For this reason, there is an increasing demand for a“nano-coating material” which exhibits a high antirust effect even if afilm having a small thickness in the order of nanometers.

Furthermore, a nano-coating material having excellent adhesive power fora metal is expected to be applicable to an antirust coating material, aswell as various applications such as, for example, a coating agent foran electrode of a battery.

CITATION LIST Patent Literatures

Patent Literature 1: JP 2004-197151 A

Patent Literature 2: JP 2009-249690 A

Non-Patent Literatures

Non-Patent Literature 1: Anton Kokalj, Sebastijan Peljhan, MatjazFinsgar, and Ingrid Milosev, Journal of The American Chemical Society,2010, 132, 16657.

Non-Patent Literature 2: H. Lee, S. M. Dellatore, W. M. Miller, and P.B. Messersmith, Science, 2007, 318, 426.

SUMMARY OF INVENTION Technical Problem

Objective of the present invention is to solve the conventional problemssuch as described above, and to provide a new nano-coating materialwhich can be applied easily, can be conveniently produced and prepared,and has excellent adhesiveness to a metal or an alloy even if the filmthickness is thin; a method for producing the nano-coating material; acoating agent; a functional material; and a method for producing thefunctional material. Particularly, it is an object of the invention toprovide a nano-coating material which also has an excellent antirusteffect in addition to the adhesiveness to a metal, an alloy or the like.

Solution to Problem

The nano-coating material of the present invention is characterized bythe following.

(1) A nano-coating material, capable of being bonded to the surface of ametal or an alloy substrate,

the nano-coating material includes a compound having, in a polymer mainchain,

(A) a first side chain or a terminal, each having a binding groupcontaining a benzene ring having at least one pair of adjacent hydroxylgroups; and

(B) a functional second side chain.

(2) The second side chain is hydrophobic.

(3) The second side chain is hydrophilic.

(4) The polymer main chain is a polymer chain including carbon (C)single bonds.

(5) The polymer main chain is formed from a copolymer of acrylamide andan acrylate.

(6) The binding group of the first side chain includes a catechol group.

(7) The second side chain has an alkyl group having a number of carbonatoms (C) of from 1 to 12.

(8) The second side chain has a functional group containing a benzenering.

The method for producing a nano-coating material of the presentinvention is characterized by the following.

(9) A method for producing a nano-coating material capable of beingbonded to the surface of a metal or an alloy, the method includes:

a polymerization step for polymerizing a first monomer having a bindinggroup containing a benzene ring having at least one pair of adjacenthydroxyl groups, and a second monomer having a hydrophobic group or ahydrophilic group.

(10) The first monomer has a methacryalmide group.

(11) The second monomer has a methacrylate group.

(12) The methacrylamide group has a hydroxyl group or an alkyl grouphaving a number of carbon atoms (C) of from 1 to 12.

(13) The acrylate group has a hydroxyl group or an alkyl group having anumber of carbon atoms (C) of from 1 to 12.

(14) The hydrophobic group includes an alkyl group having a number ofcarbon atoms (C) of from 1 to 12, or a benzene ring.

(15) In the polymerization step, the first monomer and the secondmonomer are polymerized by a thermal reaction using AIBN as apolymerization initiator.

(16) A coating agent of the present invention is for a substrate formedfrom a metal or an alloy, the coating agent including the nano-coatingmaterial.

The functional material of the present invention is characterized by thefollowing.

(17) The nano-coating material is bonded to the surface of a substrateformed from a metal or an alloy.

(18) A nano-coating film is formed on the surface of the substratethrough bonding of the nano-coating material, and the film thickness ofthe nano-coating film is 100 nm or more and less than 1 μm.

(19) The substrate is a lithium ion battery electrode.

The method for producing a functional material of the present invention

(20) A method for producing a functional material includes:

a step of dispersing the nano-coating material in an organic solvent,and preparing a nano-coating material dispersion liquid; and

a step of applying the nano-coating material dispersion liquid on asubstrate surface by a wet coating method, subsequently drying thedispersion liquid, and thereby bonding the nano-coating material to thesubstrate surface.

ADVANTAGEOUS EFFECTS OF INVENTION

The nano-coating material of the present invention can be dispersed inan organic solvent and then can be applied easily, uniformly andsmoothly by a wet coating method, and binding groups that are capable ofcoordination bonding to metal atoms can strongly adhere the coating filmto a metal surface. Particularly, in a case in which the second sidechain is hydrophobic, hydrophobic groups can prevent penetration ofwater molecules to the surface of a substrate formed from a metal or analloy. Therefore, a nano-coating material which is capable of forming acoating film having a high antirust effect even if the film thickness isthin, is provided.

Furthermore, the nano-coating material of the present invention can beused as, for example, a binder for a lithium ion battery electrode.

Furthermore, according to the method for producing a nano-coatingmaterial of the present invention, a nano-coating material that has, ina polymer main chain, a side chain having a binding group formed from abenzene ring having at least one pair of adjacent hydroxyl groups, andhas a functional second side chain, can be produced conveniently andeasily with high yield.

Regarding the functional material of the present invention, bindinggroups of a nano-coating film obtained from the coating materialdescribed above are strongly adhered by being coordinately bonded tometal atoms at the surface of a substrate formed from a metal or analloy. Particularly, in a case in which the second side chain ishydrophobic, since hydrophobic groups prevent access of water moleculesto the substrate surface, even if the film thickness of the coating filmis small in a nano-scale, an excellent antirust effect is obtained, andthe surface of a substrate of a metal, an alloy or the like can bereliably stably protected.

In the method for producing a functional material of the presentinvention, as the method includes a step for dispersing the nano-coatingmaterial described above in an organic solvent, and preparing a coatingmaterial dispersion liquid; and a step for applying the coating materialdispersion liquid on a substrate surface by a wet coating method,subsequently drying the dispersion liquid, and thereby forming anano-coating film on the substrate surface, even if the film thicknessis very small in a nano-scale, binding groups capable of coordinatebonding to metal atoms can strongly adhere the nano-coating film to ametal surface. Particularly, in a case in which the second side chain ishydrophobic, a functional material in which hydrophobic groups canprevent approach of water molecules to the surface of a substrate formedfrom a metal or an alloy, can be easily obtained.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1(a) to 1(f) are outline explanatory diagrams for the chemicalstructure of a nano-coating material according to an embodiment of thepresent invention.

FIGS. 2(a) and 2(b) show diagrams illustrating an example of forming anantirust nano-coating film according to an embodiment of the presentinvention on a metal/alloy substrate, the diagrams including (a) a planview diagram, and (b) a cross-sectional view diagram of (a) cut at theline A-A′.

FIG. 3 is a magnified outline diagram illustrating the state ofmolecular bonding of part B in FIG. 2(b), the diagram illustrating anexample of the principle of adhesion of an antirust nano-coating film ina case in which the nano-coating materials represented by chemicalformulae (2) and (4) are used for an antirust nano-coating film 11, andmetal Mg or a Mg alloy is used as a metal/metal alloy substrate 12.

FIG. 4 is an outline diagram illustrating an example of the principle ofadhesion of an antirust nano-coating film (polymer coating) in a case inwhich a metal/metal alloy substrate (metal Mg or a Mg alloy) is used.

FIG. 5 is an optical photograph of the sample of Example 1.

FIG. 6 is a graph illustrating the 1H-NMR analysis results correspondingto the polymer structure of the sample of Example 2.

FIG. 7 is a graph illustrating the 1H-NMR analysis results correspondingto the polymer structure of the sample of Example 3.

FIG. 8 is an optical photograph of the sample of Example 4.

FIG. 9 is a graph illustrating the 1H-NMR analysis results correspondingto the polymer structure of the sample of Example 6.

FIG. 10 is a graph illustrating the IR spectral analysis results for thesample of Example 6.

FIG. 11 is a graph illustrating the GPC analysis results for the sampleof Example 11.

FIG. 12 is an optical photograph of the sample of Example 12.

FIGS. 13(a) and 13(b) are schematic diagrams of a disc specimen, FIG.13(a) being a plan view diagram, and FIG. 13(b) being a cross-section of(a) cut at the line D-D′.

FIG. 14 is an optical photograph of a disc specimen.

FIGS. 15(a) and 15(b) show a coating process explanatory diagram and anoutline diagram of an adhered part of a coating film, respectively.

FIGS. 16(a) and 16(b) show schematic diagrams of the specimen of Example1, FIG. 16(a) being a plan view diagram, while FIG. 16(b) being across-sectional view diagram of (a) cut at the line E-E′.

FIG. 17 is a graph illustrating the relations between the hydrogengeneration amount of hydrogen generated when various specimens areimmersed in an acidic aqueous buffer solution (pH 5), and the immersiontime.

FIGS. 18(a) to 18(c) show SEM photographs of the surface in a casewithout a coating film, respectively corresponding to the cases of (a)immediately after polishing, (b) after immersion for 10 hours in anacidic (pH 5) buffer, and (c) after immersion for one day in a 3.5 wt %aqueous solution of NaCl.

FIGS. 19(a) to 19(c) show SEM photographs of a substrate surface in acase in which a coating film (Copoly4b-8 wt % (specimen of Example 5))was formed, respectively corresponding to the cases of (a) immediatelyafter film formation, (b) after immersion for 4 days in an acidic (pH 5)buffer, and (c) after immersion for 4 days in a 3.5 wt % aqueoussolution of NaCl.

FIG. 20 is an outline explanatory diagram for this dip-coating method.

FIGS. 21(a) and 21(b) show SEM image photographs of the surface of thespecimen of Example 7 (dip), respectively corresponding to the cases of(a) before surface coating, and (b) after surface coating.

FIG. 22 is the XPS spectrum of the surface of the specimen of Example 7(dip).

FIG. 23 is a graph illustrating the relations between the sampleconcentration in the dispersion liquid and the film thickness.

FIG. 24 is an outline explanatory diagram for the measurement of theamount of H₂ generation.

FIG. 25 is a graph illustrating the relations between the immersion timeand the amount of H₂ generation for a specimen immersed in an acidicaqueous solution (pH 5), the graph showing the dependency of thematerial.

FIGS. 26(a) and 26(b) show SEM images of portions of the specimen(Uncoated) of Comparative Example 1, respectively corresponding to thecases of (a) before immersion in an acidic aqueous solution (pH 5), and(b) after immersion for 12 hours.

FIGS. 27(a) and 27(b) show SEM images of portions of the specimen(PMMA-coated) of Comparative Example 2, respectively corresponding tothe cases of (a) before immersion in an acidic aqueous solution (pH 5),and (b) after immersion for 12 hours.

FIGS. 28(a) and 28(b) show SEM images of portions of the specimen(DOMA-MMA coated) of Example 7 (spin), respectively corresponding to thecases of (a) before immersion in an acidic aqueous solution (pH 5), and(b) after immersion for 12 hours.

FIG. 29 is a graph illustrating the relations between the immersiontimes and the amounts of H₂ generation for the specimen (DOMA-MMA) ofExample 7 (spin) and the specimen (PMMA) of Comparative Example 2.

FIGS. 30(a) and 30(b) show digital photographs of the whole specimen(PMMA) of Comparative Example 2, respectively corresponding to the casesof (a) before immersion in an acidic aqueous solution (pH 5), and (b)after immersion for 10 hours.

FIGS. 31(a) and 31(b) show digital photographs of the whole specimen(DOMA-MMA) of Example 7 (spin), respectively corresponding to the casesof (a) before immersion in an acidic aqueous solution (pH 5), and (b)after immersion for 24 hours.

FIG. 32 is a SEM image of a portion of the specimen (Uncoated) ofComparative Example 1, obtained after immersion in a 3.5 wt % NaClsolution for 3 days.

FIG. 33 is a SEM image of a portion of the specimen (PMMA) ofComparative Example 2, obtained after immersion in a 3.5 wt % NaClsolution for 3 days.

FIG. 34 is a SEM image of a portion of the specimen (DOMA-MMA) ofExample 7 (spin), obtained after immersion in a 3.5 wt % NaCl solutionfor 3 days.

FIGS. 35(a) and 35(b) show digital photographs of the whole specimen(PMMA) of Comparative Example 2, respectively corresponding to the casesof (a) before immersion in a 3.5 wt % NaCl solution, and (b) afterimmersion for 2 days.

FIGS. 36(a) and 36(b) show digital photographs of the whole specimen(DOMA-MMA) of Example 7 (spin), respectively corresponding to the casesof (a) before immersion in a 3.5 wt % NaCl solution, and (b) afterimmersion for 2 days.

FIG. 37 is an outline explanatory diagram of an electrochemicalcorrosion test.

FIG. 38 is a graph illustrating the results of an electrochemicalcorrosion test for the specimen (Uncoated) of Comparative Example 1, thespecimen (DOMA-MMA) of Example 7 (spin), the specimen (DOMA-HMA) ofExample 11 (spin), and the specimen (DOMA-DMA) of Example 12 (spin), thegraph showing the V-I (cathodic current) characteristics in a 3.5 wt %NaCl solution.

FIG. 39 is a graph illustrating the results of an electrochemicalcorrosion test for the specimen (Uncoated) of Comparative Example 1, thespecimen (DOMA-MMA) of Example 7 (spin), the specimen (DOMA-HMA) ofExample 11 (spin), and the specimen (DOMA-DMA) of Example 12 (spin), thegraph showing the V-I (anodic current) characteristics in a 3.5 wt %NaCl solution.

FIG. 40 shows photographs obtained before and after a corrosion test inthe absence of a polymer film (Uncoated) and in the presence of apolymer film (Polymer-coated) for disc specimens of various main metals.

FIG. 41 is a graph illustrating the results of an electrochemicalcorrosion test for the uncoated, doma-mma coated, doma-hma coated, anddoma-dma coated samples, the graph representing the V-I characteristicsin a 3.5 wt % NaCl solution. The solid line represents the resultsobtained by using a Mg alloy as the substrate, and the dotted linerepresents the results obtained by using Al as the substrate.

FIG. 42 is a graph illustrating the results of a 1H NMR analysis for thesample of Example 14.

FIG. 43 is a UV-V spectral diagram for the coating film of the sample ofExample 14 on a quartz substrate.

FIG. 44 is a photographic diagram showing the results of a Scotch tapetest for the coating film of the sample of Example 14.

FIG. 45 is a photographic diagram showing the results of a Scotch tapetest for a PMMA coating film as a Comparative Example.

FIG. 46 is a photographic diagram showing the results of a Scotch tapetest for various substrates of the samples of Example 14.

FIG. 47 is a graph illustrating the static water contact angle afterimmersion o the sample of Example 14 in aqueous solutions at variouspH's.

FIGS. 48(a) and 48(b) show diagrams showing (a) a comparison of the TGAcurve and (b) a DSC thermogram for the sample of Example 15.

FIGS. 49(a) to 49(c) show diagrams representing (a) FT-IR spectrum, (b)relations between the polymer concentration and the film thickness, and(c) water contact angle, for the sample of Example 15.

DESCRIPTION OF EMBODIMENTS

The nano-coating material of the present invention is a nano-coatingmaterial that is bonded to the surface of a substrate formed from ametal or an alloy, and the nano-coating material is formed from acompound which has, in a polymer main chain,

(A) a first side chain or a terminal, each having a binding groupcontaining a benzene ring having at least a pair of adjacent hydroxylgroups; and

(B) a functional second side chain.

Since the nano-coating material of the present invention has, in apolymer main chain, (A) a first side chain or a terminal, which has abinding group containing a benzene ring having at least a pair ofadjacent hydroxyl groups, the binding group of the first side chain,which is capable of coordinate bonding to a metal atom, is stronglybonded to the metal surface, and therefore, the nano-coating materialhas excellent adhesiveness to a metal or an alloy.

In a case in which the (B) functional second side chain, which isbranched from the polymer main chain, is hydrophobic (in the followingdescription, may be described as “hydrophobic second side chain”), thenano-coating material can be utilized as a nano-coating material havingexcellent antirust properties.

That is, in regard to the development of conventional antirust coatingmaterials, since the main purpose lies in enhancing adhesiveness or inproducing a smooth oxide film on the metal surface, in the developmentof a new antirust coating material, combining the antirust coatingmaterial with a hydrophobic material, which is considered to decreaseadhesiveness, could not be considered. However, the inventors of thepresent invention speculated that when the configuration of the antirustcoating material is functionally separated, and the antirust coatingmaterial is constructed from a polymer that has a binding group having afunction of enhancing adhesiveness to the surface of a substrate of ametal or an alloy, which requires rust proofing, and has a hydrophobicgroup capable of interrupting the approach and contact of reactivesubstances such as oxygen molecules, water molecules, or halide ions tothe substrate surface, adhesiveness could be increased, and the antirusteffect could be increased even if the film thickness is thin.

Based on such speculation, the inventors of the present inventionconducted a thorough investigation. During the course of thisinvestigation, the present inventors came across a report that Mefps5,which is blue mussel's adhesive protein, strongly adheres to varioussubstrates including metal Au (Non-Patent Literature 2). During aninvestigation of this report, the present inventors paid attention tothe fact that Mefps5 has dopamine. The present inventors synthesizedpoly(dopamine methacrylamide-co-alkyl methacrylate) and adopamethacrylamide-styrene copolymer, by combining a binding grouphaving a skeleton of dopamine and a hydrophobic group. Thus, theinventors found that when an antirust nano-coating film containing thesepolymers as nano-coating materials is formed on the surface of a Mgalloy substrate, the antirust nano-coating film can be easily applied onthe Mg alloy substrate and can be strongly adhered thereto, and even ifthe film thickness is thin, the approach and contact of corrosivereactive substances to the substrate surface can be interrupted, so thata noticeable antirust effect can be obtained. The present inventorsconducted a further investigation based on these findings, and therebycompleted a new nano-coating material.

(Nano-Coating Material)

In regard to the nano-coating material of the present invention, anembodiment in which the functional second side chain is hydrophobic willbe explained.

The nano-coating material of this embodiment is adhered to the surfaceof a substrate formed from a metal or an alloy, as a nano-coating filmhaving a nano-sized film thickness, and can prevent the approach ofwater molecules to the substrate surface.

The nano-coating material of this embodiment has, in a polymer mainchain,

(A) a first side chain or a terminal, which has a binding groupcontaining a benzene ring having at least a pair of adjacent hydroxylgroups; and

(B) a hydrophobic second side chain.

Here, the “benzene ring having at least a pair of adjacent hydroxylgroups” means a benzene ring having two or more hydroxyl groups, inwhich at least any two of these hydroxyl groups are adjacent to eachother.

Furthermore, the “binding group” means an organic constituent group thatis bonded to the surface of a substrate formed from a metal or an alloyand enables binding and adhesion of a coating material. Furthermore, theterm “nano” according to the present invention means a scale of 1(micrometer) or less, that is, 1000 nm or less.

The polymer main chain in the nano-coating material of the presentinvention may be any of various polymer chains as long as the purposeand effects of the present invention can be realized thereby, and therealization is not inhibited. For example, the polymer main chain may becomposed of carbon (C)-carbon (C) chain-like bonds, and in regard to thecarbon (C)-carbon (C) chain-like bond, the bond may be interrupted by aheteroatom, for example, an oxygen atom or a nitrogen atom, or may beinterrupted by a carbon (C) ring or a heterocyclic ring. A morepreferred example thereof is a carbon (C)-carbon (C) chain-like bond.Furthermore, in regard to the binding group of the (A) first side chain,various binding groups such as described above may be used as long asthe binding groups have a benzene ring having at least a pair ofadjacent hydroxyl groups. Here, the benzene ring may be a monocyclicring, or may be a member constituting a polycyclic ring or aheterocyclic ring. Furthermore, the bond between the first side chainhaving a benzene ring and the polymer main chain may also be in variousforms, such as a bond interrupted by a carbon (C) chain, a heteroatom orthe like.

The (B) hydrophobic second side chain may also be in various forms. Itis desirable that the second side chain constitutes a hydrophobicorganic group.

Embodiments will be explained below; however, first, the followingformula (2) is a chemical formula representing an example of thenano-coating material according to an embodiment of the presentinvention. As shown in formula (2), the nano-coating material accordingto an embodiment of the present invention has a polymer main chain partP, a first side chain R₁ having a binding group, and a hydrophobicsecond side chain R₂.

The polymer main chain part P may be a polymer chain composed of singlebonds of carbon (C), that is, a polymer main chain having an alkylchain. When an alkyl chain is used, the nano-coating material can bedispersed in an organic solvent uniformly with high dispersibility, anda smooth film that has no defects even if the film thickness is thin canbe formed easily by a wet coating method such as a spin coating method.For example, a suitable example of the polymer main chain part P may bean alkyl chain formed from a copolymer of acrylamide and an acrylate.Each of symbols R₃ and R₄ in the polymer main chain part P represents ahydrogen atom or an organic group. The organic group may be of variouskinds as long as the purpose and effects of the present invention arenot impaired. For example, R₃ and R₄ each represent a hydroxyl group, ora linear or branched alkyl group having from 1 to 12 carbon (C) atoms,and they may be identical to or different from each other. Examplesthereof include a methyl group and an ethyl group.

The ratio m:n between the main chain portion having the first side chainR₁ and the main chain portion having the second side chain R₂ ispreferably adjusted to from 1:6 to 1:100. Thereby, polymerization can beachieved with high yield. Furthermore, a reliable antirust coatingeffect may be obtained.

The following formula (3) is a chemical formula representing a preferredexample of the side chain R₁.

The side chain R₁ shown in formula (3) has a binding group Z.

The binding group Z is an organic group capable of coordinate bonding toa metal atom at the surface of a substrate formed from a metal or analloy. The binding group Z has a benzene ring having at least one pairof adjacent hydroxyl groups. For example, the binding group Z is acatechol group represented by the following formula (4).

For example, when the binding group includes such a chemical structurehaving a benzene ring having at least one pair of adjacent hydroxylgroups, the oxygen of the adjacent hydroxyl groups are coordinate bonded(chelate bonded) to the metal atoms that constitute the metal substrate,and thereby the coating film can be strongly adhered to the surface ofthe metal substrate.

Of course, the binding group Z may be configured such that the benzenering has three or more hydroxyl groups. When this configuration isadopted, the number of coordinate bonds formed with metal atoms perfunctional group increases, and the adhesive power can be enhanced.

FIGS. 1(a) to 1(f) are outline explanatory diagrams for the chemicalstructure of the nano-coating material according to an embodiment of thepresent invention. In FIG. 1(a), the binding group Z is shown in theballoon, and it is shown that a catechol group is used as an example ofZ. FIG. 1(b) to FIG. 1(f) illustrate examples of the chemical structureconcerning the disposition of the binding group Z in the nano-coatingmaterial. FIG. 1(b) illustrates a material in which this binding group Zis linked to a terminal side of a linear polymer main chain part P; FIG.1(c) illustrates a material in which this binding group Z is linked toboth terminal sides of a linear polymer main chain part P; FIG. 1(d)illustrates a material in which binding group Z is linked to a shortfirst side chain of a linear polymer main chain part P; FIG. 1(e)illustrates a material in which the binding group Z is linked to bothterminal sides and a long first side chain of a linear polymer mainchain part P; and FIG. 1(f) illustrates a material in which this bindinggroup Z is linked to the terminal sides of a cross-shaped polymer mainchain part P. When the parts P are mutually entangled, film stability isincreased.

Furthermore, the nano-coating material may also be configured such thatthe first side chain R₁ has plural binding groups Z. Thereby, the numberof adhesive moieties in one side chain can be increased, and theadhesive power can be enhanced.

The second side chain R₂ is hydrophobic. When the nano-coating materialis configured to include a hydrophobic second side chain R₂, a metalsurface can be covered with a polymer film having the second side chainR₂. Thus, for example, water molecules can be prevented from approachingthe surface of a metal substrate, and metal atoms reacting with watermolecules and forming rust can be suppressed.

The following formula (5) shows an example of the second side chain R₂,which has a hydrophobic group R₅.

A suitable example of the hydrophobic group R₅ of formula (5) may be analkyl group having a number of carbon atoms (C) of from 1 to 20. In acase in which the number of carbon atoms (C) is set to 0, that is, in acase in which the functional group R₅ is not provided, even if a coatingfilm is formed, a waterproofing effect may not be obtained, and rust isformed. Furthermore, when the number of carbon atoms is set to more than16, the alkyl chain becomes too long, and it becomes difficult toachieve solubilization in an organic solvent, which is needed for filmproduction.

Specific examples of the hydrophobic group R₅ include a methyl group, anethyl group, a n-propyl group, an isopropyl group, a n-butyl group, asec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group,a n-hexyl group, a n-heptyl group, a n-octyl group, a n-nonyl group, an-decyl group, a n-undecyl group, and a n-dodecyl group.

Furthermore, formula (6) shows another example of the second side chainR₂, and is formed from a hydrophobic functional group.

In formula (6), the second side chain R₂ is a phenyl group, which is ahydrophobic functional group. The benzene of the phenyl group may bereplaced with a benzene having a further substituent. For example,methylbenzene or anisole (methoxybenzene) may also be used.

Furthermore, not only a benzene ring, but also a functional group havinga polycyclic aromatic hydrocarbon (PAH) such as perylene or pyrene maybe used, and particularly, a functional group having an acene-basedpolycyclic aromatic hydrocarbon such as naphthalene, anthracene orpentacene may also be used.

As such, the nano-coating material of this embodiment is formed from acompound which has, in a polymer main chain, (A) a first side chain or aterminal, each having a binding group containing a benzene ring havingat least one pair of adjacent hydroxyl groups, and (B) a hydrophobicsecond side chain. For example, a preferred example of a compound havingexcellent adhesiveness to a substrate is the following compound.

Since P(DOMA-HMA) has a catechol group in a first side chain, thebinding group capable of coordinate bonding to a metal atom can stronglyadhere the coating film to the metal surface. Furthermore, sinceP(DOMA-HMA) has a hydrophobic second side chain, and the hydrophobicgroup can prevent the approach of water molecules to the surface of asubstrate formed from a metal or an alloy, the material can be utilizedas a nano-coating material having antirust properties.

Since the nano-coating material of the present invention can have, forexample, an ionic group that assists ion transportation, an ethyleneglycol group or the like freely introduced thereinto, the nano-coatingmaterial can be applied to various applications. Furthermore, thenano-coating material of the present invention can be imparted withsolubility that is necessary according to various applications by, forexample, controlling the counter part of the catechol group.

(Method for Producing a Nano-Coating Material)

Next, an embodiment of the method for producing a nano-coating materialof the present invention will be explained.

The method for producing a nano-coating material of the presentinvention includes a step for polymerizing a first monomer having abinding group containing a benzene ring having at least one pair ofadjacent hydroxyl groups, and a second monomer having a hydrophobicfunctional group.

(Monomer-Dispersed Solution Production Step S1)

In this step, the first monomer and the second monomer are dispersed inan organic solvent, and thereby a monomer-dispersed solution isproduced.

Here, in the first monomer, for example, suitably, a first side chain R₁having a binding group and an organic group R₃ are bonded to a C═Ccarbon double bond at one terminal side of this C═C carbon double bond.

In the second monomer, a hydrophobic second side chain R₂ and an organicgroup R₄ are bonded to a C═C carbon double bond at one terminal side ofthis C═C carbon double bond.

Examples of the first monomer in this case include dopaminemethacrylamide (N-(3,4-d ihydroxyphenethyl) methacrylamide).

Dopamine methacrylamide (N-(3,4-dihydroxyphenethyl) methacrylamide) hasa C═C carbon double bond, and a methyl group and a side chain containingdopamine on one terminal side of this C═C carbon double bond. Dopaminehas a binding group having a benzene ring having at least one pair ofhydroxyl substituents.

Instead of a methyl group of the methacrylamide, a hydroxyl group or alinear or branched alkyl group having a number of carbon atoms (C) offrom 1 to 12 may also be used.

Examples of the second monomer include methyl methacrylate and styrene.

Methyl methacrylate has a C═C carbon double bond, and on one terminalside of this C═C carbon double bond, a methyl group and a hydrophobicside chain formed from a methyl-ester group.

Styrene has a C═C carbon double bond, and on one terminal side of thisC═C carbon double bond, a methyl group and a hydrophobic side chainformed from a phenyl group.

In these examples, the hydrophobic second side chain R₂ is amethyl-ester group or a phenyl group. Instead of the methyl group of themethyl-ester group, a hydroxyl group or a linear or branched alkyl grouphaving a number of carbon atoms (C) of from 1 to 12 may also be used. Byhaving such a hydrophobic second side chain R₂, efficient waterrepelling can be achieved.

(Monomer Polymerization Step S2)

In this step, the monomers in the monomer-dispersed solution arepolymerized.

The following chemical reaction scheme (7) shows an example of thepolymerization reaction.

The polymerization reaction described above is carried out by, forexample, a heated reaction using AIBN (2,2′-azobisisobutyronitrile) as apolymerization initiator. Thereby, polymerization can be carried outefficiently.

For example, a heated polymerization reaction can be carried out usingmethacrylamide as a first raw material monomer and using a methacrylateas a second raw material monomer. In this case, the polymerizationreaction can be completed by using DMF as a solvent, using 1 to 2 mol%of AIBN as a polymerization initiator, and heating the system for 30 to50 hours at 70° C. to 80° C.

In chemical reaction scheme (8), an example of the polymerizationreaction in the case of using methacrylamide and a methacrylate ispresented.

Instead of a heated polymerization reaction, or in combination withthis, a photopolymerization reaction may also be carried out using aphotopolymerization initiator.

(Nano-Coating Film)

Next, an embodiment of the functional material of the present inventionwill be explained. FIG. 2 shows (a) a plan view diagram illustrating anembodiment of the functional material of the present invention, and (b)a cross-sectional view diagram of (a) cut at the line A-A′.

Regarding the substrate 12 formed from a metal or an alloy, adisc-shaped substrate 12 is used in this example. A nano-coating film 11is formed so as to cover the entire surface of the substrate 12 at auniform film thickness.

The nano-coating film 11 is formed using the nano-coating material ofthe present invention. The film thickness of the nano-coating film 11 ispreferably adjusted to from 100 nm to 1 μm. If the film thickness is 100nm or less, the approach of water molecules to the surface of thesubstrate 12 cannot be sufficiently prevented, and it is difficult toobtain a sufficient antirust effect. On the contrary, if the filmthickness is more than 1 μm, despite that the antirust effect does notchange much, the burden of the material cost increases.

Meanwhile, the nano-coating film 11 is preferably a film in which poreshaving a pore size of 50 nm or more do not exist. Thereby, the approachof water molecules to the surface of a substrate formed from a metal oran alloy can be prevented, and an antirust effect can be increased.

(Principle of Adhesion of Nano-Coating Film)

FIG. 3 is a magnified outline diagram of part B of FIG. 2(b), and is adiagram illustrating an example of the principle of adhesion of anano-coating film in a case in which the nano-coating materialrepresented by formulae (2) and (4) described above is used as thenano-coating film 11, and metal Mg or a Mg alloy is used as themetal/metal alloy substrate 12.

As illustrated in FIG. 3, the nano-coating film 11 strongly adheres tothe metal/metal alloy substrate 12 with the first side chain R₁.Specifically, the nano-coating film 11 strongly adheres to the substrate12 by means of the binding group Z of the first side chain R₁. In a casein which the binding group Z is a catechol group, adjacent hydroxylgroups of the catechol group, that is, the two adjacent hydroxyl groupsbonded to a benzene ring, strongly adhere to the Mg metal atoms of themetal/metal alloy substrate 12 by coordinate bonding.

Furthermore, the benzene rings of the catechol groups undergo π-stackingand stabilize the film, and thus a strong film is formed.

On the other hand, the nano-coating film 11 prevents contact between thesurface of the metal/metal alloy substrate 12 and water molecules andthe like, as the hydrophobic second side chain R₂ suppresses penetrationof water molecules and the like from the outside, and thereby preventsthe generation of rust at the surface of the metal/metal alloy substrate12.

FIG. 4 is also a diagram illustrating an example of the principle ofadhesion of the nano-coating film (polymer coating) in the case of usinga metal/metal alloy substrate (metal Mg or a Mg alloy).

Plural side chains from a polymer backbone, which is the polymer mainchain, are bound, and in some of the side chains (first side chains), anoxygen atom adjacent to the benzene ring functions as binding group(surface binding group) and is coordinate bonded to the metal surface,thereby adhering the film to the metal.

Furthermore, the oxygen atom of an amide bond that links this bindinggroup to the main chain, forms a hydrogen bond network with the hydrogenatoms of other amide bonds, and thus a stable film is formed.

Furthermore, another side chain (second side chain) bound to the polymermain chain is hydrophobic, and functions as an antirust polymer sidechain (anti-corrosion polymer side-chain).

(Method for Producing Functional Material)

Next, an embodiment of the method for producing a functional material ofthe present invention will be explained.

The method for producing a functional material of the present inventionhas nano-coating material dispersion liquid production step F1 andfilm-forming step F2.

(Nano-Coating Material Dispersion Liquid Production Step F1)

In this step, a nano-coating material is dispersed in an organicsolvent, and a nano-coating material dispersion liquid is produced. Inthis dispersion liquid, various additives may be added as necessary.Examples of these additives include a viscosity adjusting agent, aphotodegradation inhibitor, an antioxidant, and a colorant, and theadditives can be selected by considering the use environment,application, purpose, and the like of the antirust nano-coating film.

It is preferable that after the nano-coating material is added to anorganic solvent, the mixture is uniformly dispersed by stirringthoroughly.

Examples of the organic solvent include DMF and DMSO.

(Film-forming step F2)

In this step, the nano-coating material dispersion liquid is applied ona substrate surface by, for example, a wet coating method, and thendried, and thereby a nano-coating film is formed. The nano-coating filmcan be formed as a smooth film.

Examples of the wet coating method include a spin coating method, adipping method, and a casting method. Drying may be carried out bynatural drying of leaving the film to stand at room temperature, but mayalso be carried out by drying by heaving in an oven.

For example, in the functional material produced as such, since thenano-coating material has excellent adhesiveness to a metal or an alloyand can have an ionic group that assists ion transportation, an ethyleneglycol group or the like freely introduced thereinto, the functionalmaterial can be applied to various applications. Therefore, thefunctional material can be imparted with not only antirust propertiesbut also with various functions according to applications.

Thus, in regard to the nano-coating material of the present invention,an embodiment in which the functional second side chain is hydrophobichas been explained; however, an embodiment in which the functionalsecond side chain is hydrophilic (in the following description, may bedescribed as “hydrophilic second side chain”) is also included in thenano-coating material of the present invention. In the following, anembodiment in which the second side chain is hydrophilic will beexplained; however, parts of the explanation for the matters that arecommon in the embodiment in which the second side chain is hydrophobicwill not be repeated.

That is, a nano-coating material according to another embodiment has, ina polymer main chain,

(A) a first side chain or a terminal, which has a binding groupcontaining a benzene ring having at least one pair of adjacent hydroxylgroups; and

(B) a hydrophilic second side chain.

Examples of the hydrophilic group of the second side chain includeethylene glycol, an alkylamine, and an alkylammonium.

This embodiment also has, in a polymer main chain, (A) a first sidechain or a terminal, which has a binding group containing a benzene ringhaving at least one pair of adjacent hydroxyl groups, and since thebinding group that is capable of coordinate bonding to a metal atom isstrongly bonded to a metal surface, the nano-coating material hasexcellent adhesiveness to a metal or an alloy.

On the other hand, since the nano-coating material has a hydrophilicsecond side chain, for example, utilization thereof in a binder for alithium ion battery electrode or the like is expected.

As such, in a case in which the nano-coating material is a compoundwhich has, in a polymer main chain, (A) a first side chain or aterminal, each having a binding group containing a benzene ring havingat least one pair of adjacent hydroxyl groups, and (B) a hydrophilicsecond side chain, for example, the following compounds may be listed aspreferred examples of a material having excellent adhesiveness tosubstrates.

P(DOMA-DMAEMA) is cationic, whereas P(DOMA-PEGMA) is neutral. Thesenano-coating materials can be utilized as materials for a coating agentfor preventing lithium ions from forming needles. For example, sinceP(DOMA-DMAEMA) does not dissolve in ethylene carbonate, this substancecan be utilized as a binder for a lithium ion battery electrode, or thelike. Also for P(DOMA-PEGMA), utilization thereof as, for example, abinder for a lithium ion battery electrode is expected.

Furthermore, the method for producing a nano-coating material of thisembodiment may include a step for polymerizing a first monomer having abinding group containing a benzene ring having at least one pair ofadjacent hydroxyl groups, with a second monomer having a hydrophilicfunctional group.

Examples of the second monomer having a hydrophilic functional groupinclude ethylene glycol, an alkylamine, and an alkylammonium.

According to the present invention as described above, the followingremarkable effects are realized.

Since the nano-coating material is configured to include a polymer mainchain part P; a first side chain R₁ having a binding group Z formed froma benzene ring having at least a pair of adjacent hydroxyl groups; and afunctional second side chain R₂, the nano-coating material can bedispersed in an organic solvent and applied easily, uniformly andsmoothly by a wet coating method, and the binding group Z of the firstside chain R₁ that is capable of coordinate bonding to a metal atom canstrongly adhere the coating film to the metal surface. Furthermore, in acase in which the second side chain R₂ is hydrophobic, since thehydrophobic second side chain R₂ can prevent the approach of watermolecules and the like to the surface of a substrate formed from a metalor an alloy, a nano-coating material which is capable of forming acoating film that has a high antirust effect even if the film thicknessis thin, can be provided.

Also, since the nano-coating material of the present invention has aconfiguration in which the polymer main chain part P is a polymer chaincomposed of single bonds of carbon atoms (C), the nano-coating materialcan be dispersed in an organic solvent and applied easily, uniformly andsmoothly by a wet coating method, and a nano-coating material which iscapable of forming a nano-coating film having a high antirust effect canbe provided.

Since the nano-coating material of the present invention has aconfiguration in which the polymer main chain part P is composed of acopolymer of acrylamide and an acrylate, the nano-coating material canbe dispersed in an organic solvent and applied easily, uniformly andsmoothly by a wet coating method, and thus, a nano-coating materialwhich is capable of forming a nano-coating film that exhibits excellentadhesiveness to a metal or an alloy even if the film thickness is thin,can be provided.

The nano-coating material of the present invention is configured suchthat the binding group Z is a catechol group, the binding group of thefirst side chain R₁ that is capable of coordinate bonding to a metalatom can strongly adhere the coating film to the metal surface, and anano-coating material which is capable of forming a coating film thatexhibits excellent adhesiveness to a metal or an alloy even if the filmthickness is thin, can be provided.

Since the nano-coating material of the present invention is configuredsuch that the functional (hydrophobic) second side chain R₂ has an alkylgroup having a number of carbon atoms (C) of from 1 to 12, thehydrophobic second side chain R₂ can prevent the approach of watermolecules and the like to the surface of a substrate formed from a metalor an alloy, and therefore, a nano-coating material which is capable offorming a coating film that exhibits excellent adhesiveness to a metalor an alloy even if the film thickness is thin, can be provided.

Since the nano-coating material of the present invention is configuredsuch that the functional (hydrophobic) second side chain R₂ is afunctional group containing a benzene ring, the approach of watermolecules and the like to the surface of a substrate formed from a metalor an alloy can be prevented, and therefore, an antirust coatingmaterial which is capable of forming a coating film that has a highantirust effect even if the film thickness is thin can be provided.

The method for producing a nano-coating material of the presentinvention is configured to include a step for dispersing a first monomerhaving a binding group that has a benzene ring having at least one pairof adjacent hydroxyl substituents, and a second monomer having ahydrophobic group or a hydrophilic group in an organic solvent, andthereby producing a monomer-dispersed solution; and a step forpolymerizing the monomers in the monomer-dispersed solution. Therefore,a nano-coating material having a polymer main chain, a first side chainhaving a binding group that has a benzene ring having at least one pairof adjacent hydroxyl groups, and a hydrophobic second side chain can beproduced easily with high yield.

Since the method for producing a nano-coating material of the presentinvention is configured such that the first monomer has an acrylamidegroup, and the acrylamide group has a hydroxyl group or an alkyl grouphaving a number of carbon atoms (C) of from 1 to 12, a nano-coatingmaterial having a polymer main chain can be produced easily with highyield.

Since the method for producing a nano-coating material according to anembodiment of the present invention is configured such that the secondmonomer has a methacrylate group, and the methacrylate group has ahydroxyl group or an alkyl group having a number of carbon atoms (C) offrom 1 to 12, a nano-coating material having a polymer main chain can beproduced easily with high yield.

Since the method for producing a nano-coating material according to anembodiment of the present invention is configured such that thefunctional group of the functional (hydrophobic) second side chain is analkyl group having a number of carbon atoms (C) of from 1 to 12, or afunctional group containing a benzene ring, a nano-coating materialhaving a polymer main chain and a hydrophobic side chain can be producedeasily with high yield.

Since the method for producing a nano-coating material of the presentinvention is configured such that polymerization is carried out by aheated reaction using AIBN as a polymerization initiator, a coatingmaterial having a polymer main chain can be produced easily with highyield.

In the functional material of the present invention, a nano-coating filmbased on a nano-coating material is formed on the surface of a substrateformed from a metal or an alloy, and the binding group of the first sidechain or a terminal of the nano-coating material can strongly adhere toa metal atom at the metal surface through coordinate bonding.Furthermore, in a case in which the functional second side chain ishydrophobic, the hydrophobic group can prevent the approach of watermolecules to the surface of a substrate formed from a metal or an alloy,and can thereby protect the metal surface with a high antirust effect.Furthermore, since the nano-coating material of the present inventionhas excellent adhesiveness to a metal or an alloy, for example, thefunctional material of the present invention also includes a form inwhich the nano-coating material is bonded as a binder to a lithiumbattery ion battery electrode as a substrate.

Since the nano-coating film of the functional material of the presentinvention has a configuration in which the film thickness is 100 nm ormore and less than 1 μm, even if the film thickness is thin, excellentadhesiveness to the substrate surface is obtained.

The method for producing a functional material of the present inventionis configured to include a step for first dispersing the nano-coatingmaterial described above in an organic solvent, and producing anano-coating material dispersion liquid; and a step for applying thenano-coating material dispersion liquid on the substrate surface by awet coating method, followed by drying, and thereby forming anano-coating film. Therefore, the binding group that is capable ofcoordinate bonding to a metal atom can strongly adhere the coating filmto a metal surface.

The present invention is not intended to be limited to the embodimentsdescribed above, and can be carried out in various modifications withinthe scope of the technical idea of the present invention. Specificexamples of the present embodiments will be disclosed in the followingExamples. Of course, the present invention is not intended to be limitedto these Examples.

EXAMPLES Example 1

(Material Preparation and Evaluation of Characteristics)

As illustrated in the following chemical reaction scheme (9), material(DOMA1) as a first raw material monomer and material (methylmethacrylate) as a second raw material monomer were mixed at a feedratio (x:y) of (1:2.5), and then, the mixture was dispersed in DMFtogether with AIBN as a radical initiator to produce a monomer-dispersedsolution. Subsequently, while the monomer-dispersed solution was stirredat 75° C. for 40 hours, the monomer-dispersed solution was subjected toa free radical polymerization reaction. The AIBN concentration in DMFwas adjusted to 1.5 mol%.

Next, a poor solvent (acetone) was added to the monomer-dispersedsolution to cause reprecipitation, and thereby, a product in a whitepowder form (sample of Example 1) was obtained.

FIG. 5 is an optical photograph of the sample of Example 1 (indicated asDOMA-C₁).

Next, a 1H NMR analysis was conducted. According to a calculation basedon the results of the 1H NMR analysis of the sample of Example 1, theratio m:n was 1:5 in the sample of Example 1 (DOMA-C₁).

Example 2

A sample of Example 2 was produced in the same manner as in the case ofthe sample of Example 1, except that the feed ratio was set to 1:5.

Next, a 1H NMR analysis was conducted. FIG. 6 is a graph illustratingthe results of a 1H NMR analysis of the sample of Example 2. For thesample of Example 2, a molecular structure exhibiting the positions of1H corresponding to the NMR peaks is also disclosed. The ratio m:n forthe sample of Example 2, was 1:7.

Example 3

A sample of Example 3 was produced in the same manner as in the case ofthe sample of Example 1, except that the feed ratio (x:y) was set to1:10.

Next, a 1H NMR analysis was conducted. FIG. 7 is a graph illustratingthe results of a 1H NMR analysis of the sample of Example 3. For thesample of Example 3, a molecular structure exhibiting the positions of1H corresponding to the NMR peaks is also disclosed. The ratio m:n forthe sample of Example 3 was 1:14.

Example 4

A sample of Example 4 was produced in the same manner as in the case ofthe sample of Example 1, except that material (hexyl methacrylate) wasused as the second raw material monomer as illustrated in the followingchemical reaction scheme (10), and the feed ratio (x:y) was set to 1:1.

FIG. 8 is an optical photograph of the sample of Example 4 (indicated asDOMA-C₆).

The free radical polymerization reaction represented by chemicalreaction scheme (10) was carried out.

According to a 1H NMR analysis, the ratio m:n for the sample of Example4 was 1:4.

Example 5

A sample of Example 5 was produced in the same manner as in the case ofthe sample of Example 1, except that the same material as Example 4(hexyl methacrylate) was used as the second raw material monomer, andthe feed ratio (x:y) was set to 1:2.

According to a 1H NMR analysis, the ratio m:n for the sample of Example5 was 1:6. Precipitation was carried out using water.

Example 6

A sample of Example 6 was produced in the same manner as in the case ofthe sample of Example 1, except that the same material as Example 4(hexyl methacrylate) was used as the second raw material monomer, andthe feed ratio (x:y) was set to 1:4.

Next, a 1H NMR analysis was conducted. FIG. 9 is a graph showing the 1HNMR analysis results of the sample of Example 6. For the sample ofExample 6, a molecular structure exhibiting the positions of 1Hcorresponding to the NMR peaks is also disclosed. The ratio m:n for thesample of Example 6 was 1:10.

Next, an IR spectral analysis was conducted. FIG. 10 is a graph showingthe results of the IR spectral analysis of the sample of Example 6. An0-H absorption peak and a C=0 absorption peak were observed.

Example 7

A sample of Example 7 was produced in the same manner as in the case ofthe sample of Example 2, except that the time for the free radicalpolymerization reaction illustrated in chemical reaction scheme (9) wasset to 24 hours.

According to a 1H NMR analysis, the ratio m:n for the sample of Example7 was 1:7.

Example 8

A sample of Example 8 was produced in the same manner as in the case ofthe sample of Example 3, except that the time for the free radicalpolymerization reaction illustrated in chemical reaction scheme (9) wasset to 24 hours.

According to a 1H NMR analysis, the ratio m:n for the sample of Example8 was 1:14.

Example 9

A sample of Example 9 was produced in the same manner as in the case ofthe sample of Example 8, except that the feed ratio (x:y) was set to1:30.

According to a 1H NMR analysis, the ratio m:n for the sample of Example9 was 1:33.

Example 10

A sample of Example 10 was produced in the same manner as in the case ofthe sample of Example 8, except that the feed ratio (x:y) was set to1:90.

According to a 1H NMR analysis, the ratio m:n for the sample of Example10 was 1:100.

Example 11

A sample of Example 11 was produced in the same manner as in the case ofthe sample of Example 6, except that the time for the free radicalpolymerization reaction illustrated in chemical reaction scheme (10) wasset to 24 hours.

According to a 1H NMR analysis, the ratio m:n for the sample of Example11 was 1:10.

Next, a GPC analysis was carried out.

FIG. 11 is a graph showing the results of a GPC analysis of the sampleof Example 11.

Example 12

A sample of Example 12 was produced in the same manner as in the case ofthe sample of Example 1, except that material (dodecyl methacrylate) wasused as the second raw material monomer as illustrated in the followingchemical reaction scheme (11), the time for the free radicalpolymerization reaction was set to 24 hours, and the feed ratio (x:y)was set to 1:3.

FIG. 12 is an optical photograph of the sample of Example 12 (indicatedas DOMA-C₁₂).

A free radical polymerization reaction was carried out.

According to a 1H NMR analysis, the ratio m:n for the sample of Example12 was 1:6.

Example 13

A sample of Example 13 was produced in the same manner as in the case ofthe sample of Example 1, except that material (styrene) was used as thesecond raw material monomer as illustrated in the following chemicalreaction scheme (12), the time for the free radical polymerizationreaction was set to 24 hours, and the feed ratio (x:y) was set to 1:7.

A free radical polymerization reaction was carried out.

Reprecipitation was carried out using water.

According to a 1H NMR analysis, the ratio m:n for the sample of Example13 was 1:10.

Table 1 is a table presenting the synthesis conditions and the synthesisresults for the samples of Examples, and is a table presenting theabbreviations, raw material names of x and y, feed ratio (raw materialcomposition), analytic ratio (synthesized material composition),polymerization time, mass percent (%) of catechol groups, yield,molecular weight, and PDI.

Results indicating that when the proportion of DOMA increased, themolecular weight decreased, and the yield also decreased, were obtained.

TABLE 1 Feed ratio Analytic catechol (x:y) ratio Polymerization unitYield Mw PDI Name x y (initial ratio) (m:n) time (h) (wt %) (%) (gmol⁻¹)(Mw/Mn) Example 1 Doma-C₁(1:5)40 h Doma MMA  1:2.5 1:5  40 31  9 67003.01 Example 2 Doma-C₁(1:7)40 h Doma MMA 1:5 1:7  40 24 83 20300 1.97Example 3 Doma-C₁(1:14)40 h Doma MMA  1:10 1:14 40 14 89 34100 2.23Example 4 Doma-C₆(1:4)40 h Doma HMA 1:1 1:4  40 25 14 4700 2.11 Example5 Doma-C₅(1:6)40 h Doma HMA 1:2 1:6  40 18 79 20200 3.01 Example 6Doma-C₆(1:10)40 h Doma HMA 1:4 1:10 40 12 73 28800 2.46 Example 7Doma-C₁(1:7)24 h Doma MMA 1:5 1:7  24 25 71 10,300 1.97 Example 8Doma-C₁(1:14)24 h Doma MMA  1:10 1:14 24 15 84 15,200 2.23 Example 9Doma-C₁(1:33)24 h Doma MMA  1:30 1:33 24 7 89 17,800 2.46 Example 10Doma-C₁(1:100)24 h Doma MMA  1:90  1:100 24 3 81 41,000 2.70 Example 11Doma-C₆(1:10)24 h Doma HMA 1:4 1:10 24 12 73 11,700 2.46 Example 12Doma-C₁₂(1:6)24 h Doma DMA 1:3 1:6  24 14 62 25,800 1.65 Example 13Doma-Sty(1:10)24 h Doma Styrene 1:7 1:10 24 18 31 9,300 1.17

<Production of Specimen and Evaluation of Rust Characteristics>

(Production of Disc Specimen)

Next, a Mg alloy rod (commercially available product, Mg—Al3%-Zn1%alloy, Mg alloy (AZ31), diameter 1.5 cm) was cut, and a Mg alloy discwas produced. The thickness was set to 4 mm.

Next, the Mg alloy disc was disposed to be superposed on a resin cutinto a disc form, subsequently the Mg alloy disc was pressed in so as tobe completely embedded in the thickness direction, and then the surfacewas polished. Thus, a disc specimen was produced.

FIGS. 13(a) and 13(b) show schematic diagrams of a disc specimen, inwhich FIG. 13(a) is a plan view diagram, and FIG. 13(b) is across-sectional view diagram of (a) cut at line D-D′.

FIG. 14 is an optical photograph of a disc specimen.

Production of Specimen of Example 1

Next, the sample of Example 1 was dispersed in THF at a proportion of 8wt %, and a dispersion liquid was prepared.

Subsequently, the dispersion liquid 1 was spin coated so as to cover theexposed surface of Mg of the disc specimen. Spin coating was carried outunder the conditions of (for 15 seconds at 1000 rpm, and subsequentlyfor 30 seconds at 2500 rpm).

Next, the dispersion liquid was heated and maintained under theconditions of 60° C. and 1 hour and then dried, and thereby a specimenof Example 1 was produced.

FIGS. 15(a) and 15(b) show an explanatory diagram for a coating processand a conceptual diagram of the adhesion part of a coating film,respectively.

As in the case of the explanatory diagram for a coating process, a 8 wt% solution of Copolymer in THF was spin coated on one surface of asubstrate formed from a Mg alloy, and then the substrate was heated at60° C. for 1 h. Thereby, a polymer coated substrate was produced.

In the conceptual diagram of the adhesion part of a coating film, theoxygen atoms of catechol groups of the polymer adhere to the substrateby being coordinate bonded to Mg atoms that constitute the substrate. Itis illustrated that hydrophobic side chains of the polymer can standclose together and prevent the approach of water molecules and the liketo the substrate surface.

FIGS. 16(a) and 16(b) show schematic diagrams of the specimen of Example1, in which FIG. 16(a) is a plan view diagram, and FIG. 16(b) is across-sectional view diagram of FIG. 16(a) cut at line E-E′.

The specimen of Example 1 was produced such that the bottom face and theside face of the Mg disc were completely covered by the resin, while theexposed surface was covered by a coating film, and the coating film wasformed so as to also cover a portion of the resin, so that there was noexposed surface of the Mg disc. The film thickness of the coating filmwas 500 nm. Furthermore, it was confirmed by SEM observation that thecoating film was a smooth film in which pores having a pore size of 50nm or more were not formed.

Production of Specimens of Examples 2 to 13

Specimens of Examples 2 to 13 were produced in the same manner as in thecase of the specimen of Example 1, except that the samples of Examples 2to 13 were used.

Production of Specimen of Comparative Example 1

A disc specimen was used as a specimen of Comparative Example 1. Thiswas a specimen intended for analyzing the conditions in which a coatingfilm was not formed.

Production of Specimen of Comparative Example 2

A specimen of Comparative Example 2 was produced in the same manner asin the case of the specimen of Example 1, except that PMMA (polymethylmethacrylate resin) was used.

A film was formed using a 8 wt % PMMA solution.

(Evaluation of Rust Characteristics)

FIG. 17 is a graph illustrating the relations between the hydrogengeneration amount of the hydrogen generated when various specimens wereimmersed in an acidic aqueous buffer solution (pH 5), and the immersiontime.

In a case in which no coating film was provided (specimen of ComparativeExample 1), hydrogen was generated at a rate of 110 mL/cm² forapproximately 20 hours, and the substrate surface was almost rusted.

On the other hand, in a case in which the specimen was coated with aPMMA film (specimen of Comparative Example 2), an antirust effect wasobserved; however, hydrogen was generated at a rate of 55 mL/cm² forabout 40 hours.

The specimen of Example 2, the specimen of Example 3, the specimen ofExample 5, and the specimen of Example 6 exhibited antirust effects thatwere enhanced to a large extent compared to the specimens of ComparativeExamples 1 and 2. Particularly, in the specimen of Example 5, hydrogenwas generated only at a rate of 5 mL/cm² for about 95 hours, and aremarkable antirust effect was observed.

FIGS. 18(a) to 18(c) show SEM photographs of the surface in the casewithout a coating film, corresponding to the cases of (a) immediatelyafter polishing, (b) after immersion for 10 hours in an acidic (pH 5)buffer, and (c) after immersion for one day in a 3.5 wt % aqueoussolution of NaCl.

Rust was observed at the surface not only in the case of being immersedin an acidic solvent, but also in the case of being immersed in analkaline solvent.

FIGS. 19(a) to 19(c) show SEM photographs of a substrate surface in acase in which a coating film (specimen of Example 5) was formed,respectively corresponding to the cases of (a) immediately after filmformation, (b) after immersion for 4 days in an acidic (pH 5) buffer,and (c) after immersion for 4 days in a 3.5 wt % aqueous solution ofNaCl. In the case of the acidic solvent, rust was observed at thesurface; however, in the case of the alkaline solvent, rust was hardlyseen at the surface.

Furthermore, Table 2 is a table presenting the production conditions forthe specimen of Example 1 to the specimen of Example 6, and thespecimens of Comparative Examples 1 and 2, and the results of anevaluation for rust prevention.

TABLE 2 Hydrogen generation amount when immersed in acidic solutionCoating film (mL/cm²) Material Film Immersion Immersion ImmersionMaterial Coating thickness for 20 for 38 for 60 name method (nm) hourshours hours Specimen of Example 1 Spincoating 500 — — — Example 1Specimen of Example 2 Spincoating 500 1 1 15 Example 2 Specimen ofExample 3 Spincoating 500 1 5 20 Example 3 Specimen of Example 4Spincoating 500 — — — Example 4 Specimen of Example 5 Spincoating 500 11  1 Example 5 Specimen of Example 6 Spincoating 500 1 3  9 Example 6Specimen of — — — 110 — — Comparative Example 1 Specimen of PMMASpincoating 500 20 45  — Comparative Example 2

Production of Specimen of Example 7 (Dip)

(Production of Disc Specimen)

Next, a Mg alloy rod (commercially available product, Mg—Al 3%-Zn 1%alloy, Mg alloy (AZ31), diameter 1.5 cm) was cut, and a Mg alloy discwas produced. The thickness was set to 4 mm.

Next, the surface was wiped with SiC paper and was subjected to acleaning treatment with EtOH, H₂O, and acetone in this order. Thus, adisc specimen was produced.

Next, the sample of Example 7 was dispersed in DMF at a proportion of 2mg/mL, and a dispersion liquid was prepared.

Next, a disc specimen was immersed in the dispersion liquid that washeated to 60° C. for 6 hours, and then the disc specimen was pulled out,washed, and dried. Thereby, a specimen of Example 7 (dip) having thesurface coated in Example 7 was produced.

FIG. 20 is an explanatory diagram for this dip-coating method.

Surface Evaluation of Specimen of Example 7 (Dip)

First, the surface was observed by SEM. FIGS. 21(a) and 21(b) show SEMimage photographs of the surface of the specimen of Example 7 (dip),respectively corresponding to the cases of (a) before surface coatingand (b) after surface coating.

Next, the surface was subjected to an XPS analysis. FIG. 22 is the XPSspectrum of the surface of the specimen of Example 7 (dip). Polymerdeposited AZ31 (b) represents the XPS spectrum of the surface of thespecimen of Example 7 (dip), and Bare AZ31 (a) represents the XPSspectrum of the specimen of Comparative Example 1 measured for acomparison.

From these results of surface evaluations, it could be confirmed thatdespite having a thin film thickness, the polymer of the sample ofExample 7 strongly adhered to the metal surface as a result of aninteraction between catechol and Mg²⁺ at the surface of a Mg alloy oxidefilm. This suggests that since there appears a N1s peak originating fromthe nitrogen contained in an amide bond (NHCO) that is contained in thesample specimen, the sample specimen was adhered to the surface of theMg alloy oxide film.

Production of Specimen of Example 7 (Spin)

(Production of Disc Specimen)

After a disc specimen was produced, a film was formed thereon accordingto a spin coating method, and this was subjected to a heating and dryingtreatment at 60° C. Thus, a specimen of Example 7 (spin) was produced.The conditions for the film-forming process were (for 15 seconds at 1000rpm, and subsequently for 30 seconds at 2500 rpm).

The polymer film of the sample of Example 7 of the specimen of Example 7(spin) was transparent and was stable even in air.

Meanwhile, in order to clarify the relations between concentration andfilm thickness, dispersion liquids having different concentrations ofthe sample of Example 7 were produced, the dispersion liquids were spincoated under the same conditions, and the film thicknesses were measuredusing a surface profiler (DEKTAK). It was found that the film thicknesswas dependent on the concentration of the sample of Example 7 in adispersion liquid.

FIG. 23 is a graph illustrating the relations between the sampleconcentration in a dispersion liquid and the film thickness.

Production of Specimen of Example 11 (Spin)

A specimen of Example 11 (spin) was produced in the same manner as inthe case of the specimen of Example 7 (spin), except that the sample ofExample 11 was used.

Production of Specimen of Example 12 (Spin)

A specimen of Example 12 (spin) was produced in the same manner as inthe case of the specimen of Example 7 (spin), except that the sample ofExample 12 was used.

Table 3 presents the production conditions for the various specimens.

TABLE 3 Material name abbreviation Coating method Specimen Example 7Doma-C₁(1:7)24 h Dipcoating of Example 7 (dip) Specimen Example 7Doma-C₁(1:7)24 h Spincoating of Example 7 (spin) Specimen Example 11Doma-C₆(1:10)24 h Spincoating of Example 11 (spin) Specimen Example 12Doma-C₁₂(1:6)24 h Spincoating of Example 12 (spin)

(Evaluation of Rust Characteristics Based on Immersion in Acidic AqueousSolution (pH 5))

(H₂ Generation Amount)

Next, the specimens of Example 7 (spin), 11 (spin) and 12 (spin) andComparative Examples 1 and 2 were respectively immersed for a long timein an acidic aqueous solution (pH 5), and measurement of the H₂generation amounts was carried out.

FIG. 24 is an explanatory diagram for the measurement of the H₂generation amount.

FIG. 25 is a graph illustrating the relations between the immersion timefor a specimen that has been immersed in an acidic aqueous solution (pH5), and the H₂ generation amount, and this graph illustrates dependencyof the material.

The specimens of Example 7(spin), 11 (spin) and 12 (spin) had smaller H₂generation amounts compared to the specimens of Comparative Examples 1and 2, and the metal surface protecting effect was clearly enhanced.

(Partial SEM Image and Digital Photograph of Whole)

FIGS. 26(a) and 26(b) show SEM images of portions of the specimen(Uncoated) of Comparative Example 1, respectively corresponding to thecases of (a) before immersion in an acidic aqueous solution (pH 5), and(b) after immersion for 12 hours. Inserted diagrams are digitalphotographs of the whole specimen. In the specimen of ComparativeExample 1, fine cracks were generated over the entire surface as aresult of immersion in an acidic aqueous solution (pH 5) for 12 hours.

FIGS. 27(a) and 27(b) show SEM images of portions of the specimen(PMMA-coated) of Comparative Example 2, respectively corresponding tothe cases of (a) before immersion in an acidic aqueous solution (pH 5),and (b) after immersion for 12 hours. Inserted diagrams are digitalphotographs of the whole specimen. In the specimen of ComparativeExample 2, large cracks were generated over the entire surface as aresult of immersion in an acidic aqueous solution (pH 5) for 3 days.

FIGS. 28(a) and 28(b) show SEM images of portions of the specimen(DOMA-MMA coated) of Example 7 (spin), respectively corresponding to thecases of (a) before immersion in an acidic aqueous solution (pH 5), and(b) after immersion for 12 hours. Inserted diagrams are digitalphotographs of the whole specimen. In the specimen of Example 7 (spin),even after the specimen had been immersed in an acidic aqueous solution(pH 5) for 15 days, no change was observed at the surface.

(Digital Photograph of Whole Specimen in Cross-Cut Test)

Next, cross-cuts were inserted respectively into the specimen of Example7 (spin) and the specimen of Comparative Example 2, the specimens wereimmersed in an acidic aqueous solution (pH 5) for a long time period,and the H₂ generation amounts were measured.

FIG. 29 is a graph illustrating the relations between the immersiontimes and the H₂ generation amounts of the specimen (DOMA-MMA) ofExample 7 (spin) and the specimen (PMMA) of Comparative Example 2.

Compared to the specimen (PMMA) of Comparative Example 2, the H₂generation amount of the specimen (DOMA-MMA) of Example 7 (spin) waslowered.

FIGS. 30(a) and 30(b) show digital photographs of the whole specimen(PMMA) of Comparative Example 2, respectively corresponding to the casesof (a) before immersion in an acidic aqueous solution (pH 5), and (b)after immersion for 10 hours. In the specimen of Comparative Example 2,the entire surface was discolored after being immersed in an acidicaqueous solution (pH 5) for 10 hours.

FIGS. 31(a) and 31(b) show digital photographs of the whole specimen(DOMA-MMA) of Example 7 (spin), respectively corresponding to the casesof (a) before immersion in an acidic aqueous solution (pH 5), and (b)after immersion for 24 hours. In the specimen of Example 7 (spin), evenafter the specimen had been immersed in an acidic aqueous solution (pH5) for 24 hours, there were hardly any changes seen at the surface.

(Evaluation of Rust Characteristics Based on Immersion in Acidic AqueousSolution (pH 5))

(Partial SEM Image and Digital Photograph of Whole)

FIG. 32 is a SEM image of a portion of the specimen (Uncoated) ofComparative Example 1, which was obtained after immersion in a 3.5 wt %NaCl solution for 3 days. The inserted diagram is a digital photographof the whole specimen. In the specimen of Comparative Example 1, finecracks were generated over the entire surface as a result of immersionin a 3.5 wt % NaCl solution for 3 days.

FIG. 33 is a SEM image of a portion of the specimen (PMMA) ofComparative Example 2, which was obtained after immersion in a 3.5 wt %NaCl solution for 3 days. The inserted diagram is a digital photographof the whole specimen. Fine cracks were generated over the entiresurface.

FIG. 34 is a SEM image of a portion of the specimen (DOMA-MMA) ofExample 7 (spin), which was obtained after immersion in a 3.5 wt % NaClsolution for 3 days. The inserted diagram is a digital photograph of thewhole specimen. There were hardly any changes seen at the surface.

(Digital Photograph of Whole Specimen in Cross-Cut Test)

Next, cross-cuts were inserted respectively into the specimen of Example7 (spin) and the specimen of Comparative Example 2, and the specimenswere immersed in a 3.5 wt % NaCl solution for 2 days.

FIGS. 35(a) and 35(b) show digital photographs of the whole specimen(PMMA) of Comparative Example 2, respectively corresponding to the casesof (a) before immersion in a 3.5 wt % NaCl solution, and (b) afterimmersion for 2 days. In the specimen of Comparative Example 2, evenafter the specimen had been immersed in a 3.5 wt % NaCl solution for 2days, there were hardly any changes seen at the surface.

FIGS. 36(a) and 36(b) show digital photographs of the whole specimen(DOMA-MMA) of Example 7 (spin), respectively corresponding to the casesof (a) before immersion in a 3.5 wt % NaCl solution, and (b) afterimmersion for 2 days. In the specimen of Example 7 (spin), even afterthe specimen had been immersed in a 3.5 wt % NaCl solution for 2 days,there were hardly any changes at the surface.

(Electrochemical Corrosion Test)

Next, an electrochemical corrosion test was carried out.

First, a specimen electrode unit was produced by insulating surfacesother than the measurement surface.

FIG. 37 is an explanatory diagram for an electrochemical corrosion test.

As illustrated in FIG. 37, a specimen electrode unit is immersed in aliquid electrolyte (3.5 wt % NaCl solution) contained in a vessel,together with a reference electrode (R.E.) and a counter electrode(C.E.). The respective electrodes are connected to apotentio-galvanostat (not shown in the diagram) through wiring.

As illustrated in the explanatory diagram, after the specimen electrodeunit was attached, the system was left to stand for 10 minutes, and thecorrosion current was measured from the spontaneous potential by linearsweep voltammetry (L.S.V.) at a scan rate of 1 mV/sec.

FIG. 38 is a graph illustrating the results of an electrochemicalcorrosion test for the specimen (Uncoated) of Comparative Example 1, thespecimen (DOMA-MMA) of Example 7 (spin), the specimen (DOMA-HMA) ofExample 11 (spin), and the specimen (DOMA-DMA) of Example 12 (spin), thegraph showing the V-I (cathodic current) characteristics in a 3.5 wt %NaCl solution.

In regard to the specimen (Uncoated) of Comparative Example 1, it wasconsidered that H₂O was electrolyzed at the metal surface, electronswere taken into the electrode, and a large current flowed. On the otherhand, in regard to the coated specimen, it was speculated that nosignificant current flowed through the specimen, and the electrolysisreaction of H₂O was suppressed.

FIG. 39 is a graph illustrating the results of an electrochemicalcorrosion test for the specimen (Uncoated) of Comparative Example 1, thespecimen (DOMA-MMA) of Example 7 (spin), the specimen (DOMA-HMA) ofExample 11 (spin), and the specimen (DOMA-DMA) of Example 12 (spin), thegraph showing the V-I (anodic current) characteristics in a 3.5 wt %NaCl solution.

In regard to the specimen (Uncoated) of Comparative Example 1, it wasconsidered that Mg began to dissolve at the metal surface and suppliedelectrons, and thus a large current flowed. On the other hand, in regardto the coated specimen, it was speculated that no significant currentflowed through the specimen, and the dissolution reaction of Mg wassuppressed.

(Production of Specimen, Evaluation of Rust Characteristics, andEvaluation of Dependency on Metal Material)

(Production of Disc Specimen)

First, a Mg alloy rod (commercially available product, Mg—Al 3%-Zn 1%alloy, Mg alloy (AZ31), diameter 1.5 cm) was cut, and a Mg alloy discwas produced.

Similarly to this, a pure Cu rod (commercially available product,Cu-(99.9)%, diameter 1.5 cm) was cut, and a pure Cu disc was produced.

Furthermore, a pure Al rod (commercially available product, Al-(99)%,diameter 1.5 cm) was cut, and a pure Al disc was produced. Furthermore,a pure Fe rod (commercially available product, Fe-(99.9)%, diameter 1.5cm) was cut, and a pure Fe disc was produced. The thicknesses of thevarious discs were set to 4 mm.

Next, the Mg alloy disc was disposed to be superposed on a resin cutinto a disc form, subsequently the Mg alloy disc was pressed in so as tobe completely embedded in the thickness direction, and then the surfacewas polished. Thus, a disc specimen having a metal exposed surface (Mgalloy) was produced.

Similarly to this, the Cu alloy disc was disposed to be superposed on aresin cut into a disc form, subsequently the Cu alloy disc was pressedin so as to be completely embedded in the thickness direction, and thenthe surface was polished. Thus, a disc specimen (Cu) was produced.

Furthermore, the Al alloy disc was disposed to be superposed on a resincut into a disc form, subsequently the Al alloy disc was pressed in soas to be completely embedded in the thickness direction, and then thesurface was polished. Thus, a disc specimen (Al) was produced.

Furthermore, the Fe alloy disc was disposed to be superposed on a resincut into a disc form, subsequently the Fe alloy disc was pressed in soas to be completely embedded in the thickness direction, and then thesurface was polished. Thus, a disc specimen (Fe) was produced.

Production of specimens (Mg, Cu, Al, Fe) of Example 7

Similarly to (Production of specimen of Example 7 (spin)), a discspecimen (Mg alloy) was produced, and then a film was formed accordingto a spin coating method (for 15 seconds at 1000 rpm, and subsequentlyfor 30 seconds at 2500 rpm). This was subjected to a heating and dryingtreatment at 60° C., and thereby a specimen (Mg alloy) of Example 7 wasproduced. This is a sample produced in order to investigate thedependency on metal material, and is an object identical to the specimenof Example 7 (spin).

A specimen (Cu) of Example 7 was produced in the same manner as in(Production of specimen of Example 7 (spin)), except that the discspecimen (Cu) was used.

A specimen (Al) of Example 7 was produced in the same manner as in(Production of specimen of Example 7 (spin)), except that the discspecimen (Al) was used.

A specimen (Fe) of Example 7 was produced in the same manner as in(Production of specimen of Example 7 (spin)), except that the discspecimen (Fe) was used.

Next, the eight kinds of specimens described above were immersed in a3.5 wt % NaCl solution for 1 to 7 days, and thereby a corrosion test wasperformed.

FIG. 40 shows photographs of various alloy or metal disc specimensprovided in the state of being uncoated and in the state of beingpolymer-coated, which were obtained before and after a corrosion test.

The photographs of Uncoated-Before in FIG. 40 are photographs obtainedimmediately after the production of various alloy or metal discspecimens, and before a corrosion test. The photographs of Polymercoated-Before are photographs obtained immediately after the productionof specimens of various alloys or metals coated with polymer films, andbefore a corrosion test.

The photographs of Uncoated-After in FIG. 40 are optical photographsobtained after a corrosion test of various alloy or metal discspecimens. The photographs of Polymer coated-After are opticalphotographs obtained after a corrosion test of specimens of variousalloys or metals coated with polymer films.

In all of the specimens of Uncoated, the exposed surfaces of variousalloys or metals were corroded. On the other hand, in all of thespecimens of Polymer coated, the surfaces did not corrode.

(Electrochemical Corrosion Test)

Next, an electrochemical corrosion test was performed by the methodillustrated in the explanatory diagram for an electrochemical corrosiontest described above (FIG. 37).

First, four samples of Uncoated, doma-mma coated specimen of Example 7,doma-hma coated specimen of Example 11, and doma-dma coated specimen ofExample 12 were prepared using disc specimens (Al).

Next, specimen electrode units were produced by insulating surfacesother than the measurement surface in each sample.

Each of the specimen electrode units was immersed in a liquidelectrolyte (3.5 wt % NaCl solution) contained in a vessel, togetherwith a reference electrode (R.E.) and a counter electrode (C.E.). Therespective electrodes were connected to a potentio-galvanostat (notshown in the diagram) through wiring.

As disclosed in the explanatory diagram, after the specimen electrodeunit was attached, the system was left to stand for 10 minutes, and thecorrosion current was measured from the spontaneous potential by linearsweep voltammetry (L.S.V.) at a scan rate of 1 mV/sec.

FIG. 41 is a graph presenting the results of an electrochemicalcorrosion test for the samples of Uncoated, doma-mma coated specimen ofExample 7, doma-hma coated specimen of Example 11, and doma-dma coatedspecimen of Example 12, the graph showing the V-I (cathodic current)characteristics in a 3.5 wt % NaCl solution (dotted line in FIG. 41).

Meanwhile, for a comparison between metals, the results obtained in thecase of using a Mg alloy as shown in FIG. 38 are also presented together(solid line in FIG. 41).

Similarly to the case of using a Mg alloy, also in the case of using Al,H₂O was electrolyzed at the metal surface in the Uncoated sample,electrons were taken in the electrode, and a large current flowed. Onthe other hand, in the coated specimen, no significant current flowedthrough the specimen, and the electrolysis reaction of H₂O wassuppressed.

The results obtained as described above were summarized.

Table 4 is a table presenting the differences in the characteristicsdepending on the alloy or metal.

Here, the term E_(corr) represents (corrosion potential), and the termi_(corr) represents (corrosion current).

TABLE 4 Metal Condition E_(corr)(V) i_(corr)(μA/cm²) Uncoated −1.5650.2  Doma-mma −1.56 11.3 × 10⁻² Mg alloy {open oversize brace} Doma-hma−1.60 17.1 × 10⁻⁵ Doma-dma −1.53 39.1 × 10⁻⁴ Uncoated −0.72 4.62Doma-mma −0.79 2.21 × 10⁻⁴ Al {open oversize brace} Doma-hma −0.80 1.59× 10⁻⁴ Doma-dma −0.86 2.57 × 10⁻⁴

Example 14

(Material Preparation and Evaluation of Characteristics)

A sample of Example 14 was produced in the same manner as in the case ofthe sample of Example 5, except that the time of the free radicalpolymerization reaction represented by chemical reaction scheme (10) wasset to 24 hours.

FIG. 42 shows the results of a 1H NMR analysis for the sample of Example14.

The ratio m:n of the sample of Example 14 was 1:6. Furthermore, theyield of the polymerization reaction was 61%.

Furthermore, a dispersion liquid of the sample of Example 14 was spincoated on a quartz substrate in the same manner as in the productionexample of the specimen of Example 1 described above, and the UV-Vspectrum was obtained. FIG. 43 shows the analytic spectrum of this case.No peak was observed in the wavelength range of 400 nm to 700 nm, and itwas confirmed that the coating film was transparent.

(Scotch Tape Test)

A glass substrate and a Mg substrate were respectively subjected to acoating treatment as described above, using the sample of Example 14.

Furthermore, for a comparison, a specimen provided only a coating ofPMMA only was also prepared. FIG. 44 presents the results of a Scotchtape test for a specimen produced by adding a trace amount of RhodamineB dye to the sample of Example 14 and then performing coating.Characters “NIMS” and “N” represent the same meanings as previouslydescribed. According to the test results, it was confirmed that after 20times of the Scotch tape test, immersion in distilled water for 24hours, and further 20 times of the Scotch tape test, detachment of thecoating film did not occur.

On the other hand, in the case of the PMMA coating of ComparativeExamples, as shown in FIG. 45, it can be seen that detachment occurredonly after 2 times of the Scotch tape test.

Furthermore, FIG. 46 presents the results of a Scotch tape test obtainedin a case in which the sample of Example 14 was used to provide coatingon different substrates (Fe, Cu, and Al). It was found that in allcases, detachment of the coating film did not occur even after 20 timesof the Scotch tape test.

(Contact Angle Test)

The static water contact angles were measured in a case in which coatingfilms were formed using the sample of Example 14 on glass substrates,the coated substrates were immersed in aqueous solutions at differentpH's, and then the substrates were washed with distilled water and driedunder N₂ gas float.

The pH conditions were adjusted using 1 M HCl for pH 1 and pH 3; usingTris buffer for pH 9; and using 1 M NaOH for pH 11.

The relations between the contact angle and the immersion time are shownin FIG. 47. It was confirmed that there was no significant change in thewater contact angle of the coating film as a result of immersion atdifferent pH's.

Example 15

(Material Preparation and Evaluation of Physical Properties)

The results obtained by setting the time for the free radicalpolymerization reactions represented by chemical reaction schemes (9),(10), and (11) to 24 hours, and setting the amount of use of AIBN to 1mol %, are presented in Table 5. Polymerization reactions were carriedout.

Six kinds of polymers were obtained as the sample of Example 15.Meanwhile, the term poly2 in Table 5 represents the sample of Example14.

For these samples, Table 6 presents the average molecular weight, masspercent (%) of DOMA unit, and Tg (° C.).

TABLE 5 x:y Yield Polymer (feed ratio)^(a) m:n^(b) (%) Poly 1A 1:5  1:7 71 Poly 1B 1:10 1:14 84 Poly 1C 1:30 1:33 89 Poly 1D 1:90  1:100 81 Poly2 1:2  1:6  61 Poly 3 1:3  1:12 62 ^(a)Initial molar ratio,^(b)calculated from ¹H NMR

TABLE 6 poly(DOMA-co-AMA) M_(w) [g/mol], DOMA unit T_(g) Name (PDI) a:bwt % (° C.) Poly 1A (x = 1) 20,000 (1.97) 1:7  24 127 Poly 1B (x = 1)34,000 (2.23) 1:14 14 125 Poly 1C (x = 1) 44,000 (2.40) 1:33 6 115 Poly1D (x = 1) 111,000 (2.70)   1:100 2 115 Poly 2 (x = 6) 24,000 (1.67)1:6  18  60 Poly 3 (x = 12) 43,000 (1.65) 1:12 10 —

FIGS. 48(a) and 48(b) present the respective (a) TGA curves and (b) DSCthermograms (second heating cycle) of these samples. FIGS. 49(a) to49(c) present (a) a comparison of the FT-IR spectra; (b) the relationsbetween the polymer concentration measured by a surface profiler, andthe thickness of the coating film; and the (c) static water contactangles.

Example 16 (1) Synthesis of P(DOMA-DMAEMA)

N-(3,4-dihydroxyphenethyl) methacrylamide (DOMA) and2-(dimethylamino)ethyl methacrylate (DMAEMA) were synthesized by freeradical polymerization using azoisobutyronitrile (AIBN). A 100-mltwo-necked flask was charged with a DOMA monomer (444 mg, 2 mM) and AIBN(3 mol %), and the flask was purged three times with argon gas for 30minutes. 15 ml of dehydrated dimethylformamide (DMF) was added to theflask, and the mixture was stirred with a stirrer bar. This mixedsolution was purged with argon gas for 30 minutes, and then DMAEMA (1.57g, 10 mM) was added thereto using a syringe. Argon purging was performedfor another 10 minutes, and then the flask was placed in an oil bath at75° C. The mixture therein was stirred for 18 hours. Subsequently, thereaction solution was cooled to room temperature, and DMF was removedunder reduced pressure. A product thus obtained was dissolved inmethanol and was subjected to reprecipitation with petroleum ether. Aprecipitate thus obtained was stirred for 2 to 3 hours in the state asreceived, and the supernatant was removed by decantation. In order tofurther remove monomer components, the process of reprecipitation wasrepeated three times. The final product was obtained in the form of apolymer as a white powder. Furthermore, the polymer was dissolved inmethanol, and the solution was dialyzed using a dialysis membrane havinga cut-off molecular weight of 2,000 Da. Subsequently, the polymer thusobtained was dried (yield 1.86 g).

(2) Synthesis of P(DOMA-PEGMA)

Dopamine methacrylamide (DOMA) and poly(ethylene glycol) monomethylether methacrylate (PEGMA) were synthesized by free radicalpolymerization using AIBN. A 100-ml two-necked flask was charged withDOMA monomer (444 mg, 2 mM) and AIBN (3 mol %), and the mixture waspurged three times with argon for 30 minutes. Subsequently, 15 ml ofdehydrated dimethylformamide (DMF) was added to the reaction vessel. Thereaction solution was purged with argon gas for 30 minutes, and PEGMA (3g, 6.32 mM) was added thereto using a syringe. Subsequently, argonpurging was continued for 15 minutes, the mixture was allowed to reactfor 18 hours in an oil bath at 75° C., and then the reaction mixedliquid was cooled to room temperature. The reaction solution thusobtained was concentrated and was reprecipitated by adding the reactionsolution into diethyl ether. The precipitate was stirred for 2 to 3hours, the supernatant was removed by decantation, and thenreprecipitation was performed again with diethyl ether. A product thusobtained was obtained as a viscous gel (yield 3.88 g).

REFERENCE SIGNS LIST

11 Nano-Coating Film

12 Substrate

1. A nano-coating material, capable of being bonded to the surface of ametal or an alloy substrate, the nano-coating material comprising acompound having, in a polymer main chain, (A) a first side chain or aterminal, each having a binding group containing a benzene ring havingat least one pair of adjacent hydroxyl groups; and (B) a functionalsecond side chain.
 2. The nano-coating material according to claim 1,wherein the second side chain is hydrophobic.
 3. The nano-coatingmaterial according to claim 1, wherein the second side chain ishydrophilic.
 4. The nano-coating material according to claim 1, whereinthe polymer main chain is a polymer chain comprising carbon (C) singlebonds.
 5. The nano-coating material according to claim 1, wherein thepolymer main chain is formed from a copolymer of acrylamide and anacrylate.
 6. The nano-coating material according to claim 1, wherein thebinding group of the first side chain includes a catechol group.
 7. Thenano-coating material according to claim 1, wherein the second sidechain has an alkyl group having a number of carbon atoms (C) of from 1to
 12. 8. The nano-coating material according to claim 1, wherein thesecond side chain has a functional group containing a benzene ring.
 9. Amethod for producing a nano-coating material capable of being bonded tothe surface of a metal or an alloy, the method comprising: apolymerization step for polymerizing a first monomer having a bindinggroup containing a benzene ring having at least one pair of adjacenthydroxyl groups, and a second monomer having a hydrophobic group or ahydrophilic group.
 10. The method for producing a nano-coating materialaccording to claim 9, wherein the first monomer has an acrylamide group.11. The method for producing a nano-coating material according to claim9, wherein the second monomer has a methacrylate group.
 12. The methodfor producing a nano-coating material according to claim 10, wherein theacrylamide group has a hydroxyl group or an alkyl group having a numberof carbon atoms (C) of from 1 to
 12. 13. The method for producing anano-coating material according to claim 11, wherein the methacrylategroup has a hydroxyl group or an alkyl group having a number of carbonatoms (C) of from 1 to
 12. 14. The method for producing a nano-coatingmaterial according to claim 9, wherein the hydrophobic group includes analkyl group having a number of carbon atoms (C) of from 1 to 12, or abenzene ring.
 15. The method for producing a nano-coating materialaccording to claim 9, wherein in the polymerization step, the firstmonomer and the second monomer are polymerized by a heated reactionusing MEW as a polymerization initiator.
 16. A coating agent for asubstrate formed from a metal or an alloy, the coating agent comprisingthe nano-coating material according to claim
 1. 17. A functionalmaterial, comprising the nano-coating material according to claim 1bonded to the surface of a substrate formed from a metal or an alloy.18. The functional material according to claim 17, wherein anano-coating film is formed on the surface of the substrate throughbonding of the nano-coating material, and the film thickness of thenano-coating film is 100 nm or more and less than 1 μm.
 19. Thefunctional material according to claim 17, wherein the substrate is alithium ion battery electrode.
 20. A method for producing a functionalmaterial, the method comprising: a step of dispersing the nano-coatingmaterial according to claim 1 in an organic solvent, and preparing anano-coating material dispersion liquid; and a step of applying thenano-coating material dispersion liquid on a substrate surface by a wetcoating method, subsequently drying the dispersion liquid, and therebybonding the nano-coating material to the substrate surface.